Folk Physics for Small Children

An issue that often comes up in the teaching of introductory physics classes is students’ intuitive preconceptions of how the physical world works — often incorrect ideas about forces, velocities, interactions, etc. There’s a lot of education research on this and how to address it — some of which I’m even reasonably aware of! — but what I decided to write about is something still more primitive.

Last Sunday, I was helping my older son (almost 8) with a science fair project. He loves cars, and decided to see what’s the “best” tilt angle for a ramp that toy cars would roll down. He was rolling out a tape measure to measure distances, unfurling foot after foot along our living room floor, and my younger son (turning four today!) pointed out, “I bet it will keep going forever.” The older one rolled his eyes and pointed out that of course it won’t.